A colored filter is an optical filter exhibiting a color. It can accurately select light in a small range of wave band to be passed and reflect other undesirable wavelength. The colored filter is normally installed in front of the light source so that human eyes can receive saturated light of a certain color.
Currently, there are at least 10 methods for manufacturing a colored filter, although considering economical efficiency, stability of the manufactured product, and the requirements for the function of the colored filter such as color saturation, resolution, etc., the commonly used techniques include dyeing, pigment dispersion, printing and electrodeposition, in which pigment dispersion has become the major method for preparing the colored filter due to the advantages of the colored filter thus prepared such as high color purity, high precision, micronization, etc.
The basic mechanism of pigment dispersion is to coat a pigment photoresist agent on a transparent underlying substrate, which is then illuminated with ultraviolet light or similar light, etc., so as to allow the curing of the pigment photoresist agent to a pigment photoresist. The pigment photoresist agent comprises a pigment dispersion which primarily comprises a colored pigment, a dispersant, a binder resin and a solvent. The colored pigment in the pigment dispersion can determine the color of the pigment photoresist eventually formed.
The inventor has found during the implementation of the invention that the stability of the pigment dispersion is very important. If the pigment dispersion used has poor stability, the pigment particles in the pigment dispersion is prone to deposition or even coagulation, which directly causes the unevenness of the surface and coating of the colored film of the colored filter, thereby resulting in the generation of deficiencies such as the light leak of the colored filter, etc.